1) That posters a hypocritical asshole, because if he doesn't believe there's a statute of limitations on spoilers, he just dropped a bunch of extremely specific and recognisable ones for literally no reason.
2) Spoilers mean nothing out of context; if you have no interest in watching cape films "THANOS SNAP!" means literally fuck all to you, and never will.
"Bruce willis is a ghost!" with no other context means nothing. Nor does "I am your father!". Nor does "It was earth all along!".
Conversely, "'Luke, I am your father' is what Darth Vader is misquoted as saying to Luke Skywalker at the end of Empire Strikes Back where it is revealed that the series antagonist is related to the protagonist" is a highly specific reference that is unambiguously a spoiler to anyone who hasn't seen that film, and they know specifically what film it is referring to.
3) "I'm a huge cinephile, what's the Usual Suspects? That some kinda obscure arthouse flick?"
4) I told someone who was about to watch Shawshank Redemption once its a pretty good film, but a bit melodramatic when Tim Robbins kills himself, and they thought I was a huge asshole right up until the point I'd actually kind of made the film better for saying that.
Conversely, when I was about to watch Shawshank Redemption with someone who'd never seen it, the literal fucking DVD menu screen is a loop of the scene with Tim Robbins covered in mud and shit standing in the rain next to a freshly dug hole doing a "FREEEEEEEEEEDOM!" pose, which.... breh, thats your fucking 'press play' screen?